Create a concurrent map

transcoder/src/cmap.go

@@ -0,0 +1,56 @@
+package src
+
+import "sync"
+
+type CMap[K comparable, V any] struct {
+	data map[K]V
+	lock sync.RWMutex
+}
+
+func NewCMap[K comparable, V any]() CMap[K, V] {
+	return CMap[K, V]{
+		data: make(map[K]V),
+	}
+}
+
+func (m *CMap[K, V]) Get(key K) (V, bool) {
+	m.lock.RLock()
+	defer m.lock.RUnlock()
+	ret, ok := m.data[key]
+	return ret, ok
+}
+
+func (m *CMap[K, V]) GetOrCreate(key K, create func() V) (V, bool) {
+	m.lock.RLock()
+	ret, ok := m.data[key]
+	if ok {
+		m.lock.RUnlock()
+		return ret, false
+	}
+	m.lock.RUnlock()
+
+	// data does not exist, create it
+	m.lock.Lock()
+	defer m.lock.Unlock()
+
+	// check if another gorountine already created it before we could lock
+	ret, ok = m.data[key]
+	if ok {
+		return ret, false
+	}
+
+	val := create()
+	m.data[key] = val
+	return val, true
+}
+
+func (m *CMap[K, V]) GetOrSet(key K, val V) (V, bool) {
+	return m.GetOrCreate(key, func() V { return val })
+}
+
+func (m *CMap[K, V]) Remove(key K) {
+	m.lock.Lock()
+	defer m.lock.Unlock()
+
+	delete(m.data, key)
+}